[S17] 1930 U.S. Census, Oklahoma, Lincoln, South Creek, Fifteenth Census of the United States Schedule; Online Images, Enumeration District No. 41-35, Supervisor's District No. 10, Sheet 1A.
Line 29

The census lists Mary as 22 years old when she was married - which gives us this date range. However, if you use Louis' age at the time of marriage (28), it pushes the range forward about 1 year. But this does not make sense as they would have been married AFTER Edward was born - which was very rare back then.